. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. TISSUE. 91. rally, as the viscid excretion of some stems, and the nectar of nectaries. ii6. Sieve-tubes (Fig. 209, sie) are ducts, not lignified, colorless, having at long intervals horizontal, or oblique septa, which are perfora- ted. Sometimes the lateral walls are at different places perforated, and these are called sieve-discs. Through the perforations the proto- plasmic contents of the cells freely unite.
. The elements of botany embracing organography, histology, vegetable physiology, systematic botany and economic botany ... together with a complete glossary of botanical terms. Botany. TISSUE. 91. rally, as the viscid excretion of some stems, and the nectar of nectaries. ii6. Sieve-tubes (Fig. 209, sie) are ducts, not lignified, colorless, having at long intervals horizontal, or oblique septa, which are perfora- ted. Sometimes the lateral walls are at different places perforated, and these are called sieve-discs. Through the perforations the proto- plasmic contents of the cells freely unite. In latticed cells the mark- ings, but not the perforations of the sieve-discs, are present. They may, 207 therefore, be regarded as undeveloped sieve-tissue. The tracheary tissue (Fig. 209) comprises vessels, or ducts, with walls thickened in a spiral (Fig. 209, sp),—often modi- fied so as to be ringed (Fig. 209, an),—reticulated (Fig. 209, ret), scalariform (Fig. 209, sea), or pitted manner. The diameter is usually much greater than that of the sur- rounding cells. They contain proto- plasm when young, which disappears later, and then they are filled with air. Single closed cells, which other- wise possess the characters of vessels, are called tracheides. 117. In the lowest plants (and in the earliest stage in the development of higher plants) the cells are all alike, and the tissue is, therefore, uniform throughout. But as we Fig. 207. Colknchyma. Tig. 208. Laliciferous Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kellerman, William Ashbrook, 1850-1908. Philadelphia, J. E. Potter and Company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1883
